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GarryVolchara [31]
2 years ago
13

A cellphone store has 120 cell phones in stock. Of these, 45 have keyboards. The manager of the store wants to add more cell pho

nes with keyboards so that 40% of the stock has keyboards.
Mathematics
1 answer:
lubasha [3.4K]2 years ago
6 0

Answer:

5

Step-by-step explanation:

Let x be the number of cell phones with keyboards needed.

40% = \frac{40}{100}

\frac{x+45}{x+120} = \frac{40}{100}

x+45 = 40 -----1

x+120 = 100 -----2

You would want to make the total of 1 the same as 2.

1×\frac{100}{40}: 2.5+112.5 = 100 -----3

Now 2 and 3 are equal.

x+120 = 2.5x+112.5

Isolate the x and numbers.

120-112.5 = 2.5x-x

Simplify.

1.5x = 7.5

x = \frac{1}{1.5} × 7.5

x = 5

The manager of the store needs to add 5 more cell phones with keyboards.

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